A New Zealander has been killed after an attempt to snatch his backpack went wrong in Argentina, the Ministry of Foreign Affairs and Trade says.

Nicholas Heyward, thought to be in his early 30s, was walking with two other tourists in a park in the city of Mendoza when the group was ambushed about 4pm on Monday (about 7am NZ time today), Argentinian media reported.

The thieves reportedly tried to grab his backpack but he resisted and fell to the ground during the struggle, Todo Noticias, an Argentinian news channel, reported.

The thieves then shot Heyward before fleeing on their motorcycle.

Heyward's family is understood to live in Adelaide, South Australia.

Juan Carlos Caleri, the Mendoza police chief, told Todo Noticias that Heyward had "at least two gunshot wounds, one in the neck and another in the chest".

Heyward was believed to be still conscious when paramedics arrived, but died soon after at the scene, near the entrance to the Malvinas Argentinas stadium in General San Martin Park.

A man, who asked not to be named, said he studied with Heyward at Southern Cross University, near Lismore in New South Wales, and described him as a great guy.

"He was a super nice guy, well liked, never heard a bad word about him."

Heyward lived his early life in South Australia, before moving to Lismore to study for six or seven years, he said. For the past few years he had travelled the world and would be missed by a lot of people, he said.

"There will be some very sad people in Lismore, and all over the world after hearing this."

Two other tourists, an Australian woman and a Frenchman, were walking with Heyward at the time of the shooting and are giving statements to police.

A police helicopter searched the area, but was unable to find the offenders, one of whom was described as having a shaved head.

Initial reports suggested they might have been in their teens or minors.

Police were scouring the neighbourhood of La Favorita in Mendoza, where the offenders are believed to have fled.

The Argentinian Security Ministry also offered a reward of 40,000 pesos (NZ$5860) for information leading to the arrest of the offenders.

A police officer in Mendoza told Fairfax Media tonight that the attack was an isolated incident, but that there were areas of the city that tourists should steer clear of - including parts of General San Martin Park where Heyward died.

He stopped short of saying the attack happened in one of these "insecure" areas, but added there were times of the day when the park was "not safe". "It's safe in normal hours, and if you don't move away from areas with plenty of people," said Mendoza police supervisor Helvio Sosino. No wave of tourist muggings was occurring in Mendoza.

"It's a long time since anything like this happened to us." But he recommended that backpackers and other visitors always sought advice from tourist authorities and specialised "tourist police" on arrival in any new area.

"Then they can enjoy great views and they'll run the least risk." Heyward had been staying at Itaka Hostel in Mendoza since Saturday.

Fabyan Calle, who works at the hostel, told Fairfax Media the police came to the hostel after the New Zealander's death.

"We can't talk to his friends or anything, they are with the police right now," Calle said.

"We just heard the news, and then after that the police came here.

"I know that they were by the park and someone tried to mug him," Calle said.

"He went outside from the hostel this morning and never came back."

Heyward had been staying at the hostel with two companions and had been due to check out tomorrow. The companions are believed to be the pair who were with him when he was shot.

"I think they were friends, the three of them. I think with the French guy, they met two weeks ago here in Argentina and started travelling together." General San Martin Park was generally safe, Calle said.

"The main part is not too dangerous but [other parts] could be. We're always trying to tell the tourists which part to go to," he said.

Mendoza is on the eastern side of the Andes and is a popular stopover destination for adventure travellers and climbers heading into the mountains.